Due to limitations affecting voice quality, which of the broadband speeds shown is preferred in order to achieve highest voice quality on a converged data and voice teleworker connection?（）

• A、DSL with 128k uplink /128k downlink
• B、cable with 256k uplink /256k downlink
• C、DSL with 128k uplink /768k downlink
• D、cable with 256k uplink /1.4M downlink